Periodic Table O- Level Chemistry is what I call a buffer topic in O Level Chemistry. It is a relatively easy-to-understand topic and there isn’t too much to memorize. In this chapter, students are tested on the general trends in the periodic table, Group I metals, Group VII halogens, Group 0 noble gases, and transition metals.
Most of the topics involve remembering the colours, and trends of the various elements. In terms of reactions, there are just 2 reactions. These are quite important reactions since they come up frequently in exams.
One reaction is the reaction between Group I metals with water to form group I hydroxide (also known as alkalis) and hydrogen. The other reaction is the displacement reaction of halogens.
Reaction of Group I Metals with Water
Group I metals are very reactive, and they react vigorously with water, with the reaction becoming more vigorous on going down the group.
The word equation of the reaction can be written as:
group I metal + water –> group I hydroxide + hydrogen gas
Using sodium as an example:
sodium + water –> sodium hydroxide + hydrogen gas
Displacement Reaction of Group VII halogens
In this displacement reaction, the more reactive halogen will displace the less reactive halogen from its aqueous salt solution. To compare reactivity, you have got to use the fact that reactivity of halogens decrease down the group.
The reaction between aqueous chlorine and potassium bromide solution is an example of a displacement reaction.
In this reaction, the more reactive chlorine displaces bromide from its solution to form potassium bromide and bromine.
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